Depth resolved study of impurity sites in low energy ion implanted As in Si

An extended x-ray absorption fine structure investigation in depth-resolved mode allows us to identify the different sites of the arsenic along its concentration profile in shallow junctions, obtained by low energy arsenic implantation of silicon. In the deeper part of the sample, arsenic mainly occupies substitutional sites and vacancy-arsenic complexes are evidenced, whereas in the region close to the surface a mixed phase of arsenic aggregates and arsenic impurities is present. First principles calculations supporting the observations are presented. (c) 2007 American Institute of Physics.